The invention relates to a device for open-end friction spinning with two adjacently arranged rollers driven in the same direction and defining a yarn forming wedge-shaped gap therebetween. Also included are a fiber inlet and opening device, a suction device for guiding fibers and holding the forming yarn in the wedge-shaped gap, a withdrawal device for withdrawing the formed yarn in the longitudinal direction of the wedge-shaped gap, and a suction channel connectable with a vacuum pressure source and effective essentially in the longitudinal direction of the wedge-shaped gap against the withdrawal direction for drawing in a yarn end to be pieced.
With a device of the above-noted kind as disclosed in European Published Unexamined Patent Application EP-OS No. 34 427 it is known during a piecing operation to lift up the winding spool from the drive, to unwind an already spun yarn end and to shorten the same to a predetermined length. The yarn end is then transported, in bypassing relationship to the continuously running withdrawal device, to a yarn suction channel. By means of the vacuum pressure created by the suction device, the yarn end is sucked into the spinning aggregate. It is provided that a suction slot of the suction device can be closed gradually by degrees against the withdrawal direction of the yarn so that the yarn end is further sucked into the spinning aggregate. In the extension of the wedge-shaped gap at the side opposite the withdrawal device, there is further a suction channel provided which then takes over the sucking in of the yarn end.
It is also disclosed in EP-OS No. 52 412 that the rollers of friction spinning aggregates must be cleaned from time to time, especially after a yarn break. With the known construction, it is therefore provided that the one roller is moveable away from the other roller so that the rollers and the wedge-shaped gap formed by same are accessible for manual cleaning. This work is tedious and the results are dependent upon the care of the servicing personnel. Furthermore there is a very high constructive expenditure required especially for the bearings of the rollers because it is absolutely necessary that the rollers in spite of their relative movement with respect to one another, be held in exact positions with respect to one another when in the operating position.
An object of the present invention is to so construct a device of the above-mentioned kind that a cleaning operation, especially of the region of the wedge-shaped gap, can be carried out effectively and reliably.
Another object of the present invention is to carry out this cleaning operation without incurring unacceptably high construction costs in manufacturing the spinning machine.
These and other objects of the present invention are attained in the provision of means to connect the suction channel to a device to create a cleaning air stream effective in the wedge-shaped gap. According to the invention, these means comprise an already provided construction part used for another function, which auxiliary-wise can carry out a cleaning function. The construction expenditures are themselves maintained relatively small. Furthermore an effective cleaning can be carried out without moving the rollers with respect to one another.
In a further development of the invention, it is provided that the device for creating the cleaning air stream is connected with an air pressure source. With the help of a pressure air stream as a cleaning air stream, one obtains relatively high forces so that an effective cleaning is possible.
In further developments of the invention a traveling servicing device is provided which includes a device adjustably connected to the suction channel for creating the cleaning air stream. Thereby, it is assured that the cleaning of the region of the wedge-shaped gap is not dependent upon the care of the cleaning personnel or servicing personnel. Accordingly, assurance is provided that before the piecing, the same cleaning is carried out so that the same conditions exist for each piecing operation.
In constructively advantageous embodiments it is provided that the servicing device is provided with an adjustable connection line for connecting with the suction channel and with a switching device inside of the servicing device for selectively connecting the connecting line with a pressure air source or a vacuum pressure source. Advantageously, the creation of the suction air stream for the drawing in of the yarn end for a piecing operation uses elements of the servicing device which also take over a function for the cleaning so that the auxiliary expenditures for the cleaning can be maintained low.
In further developments of the invention it is provided that the suction device is provided with means for reducing and/or switching off the vacuum pressure, preferably from the servicing unit. Thereby, on the one hand, it is achieved that the return guidance of the yarn end is simplified because it is then a knot grasped by the rollers. On the other hand it is achieve that during a cleaning, by means of the air pressure stream, the loosened contaminants or particles are not held at the outer surfaces of the rollers.
In further developments of the invention the servicing unit is provided with an adjustable device for receiving the contaminants and which engages with the circumference of the rollers in the region of the wedge-shaped gap. Thereby it achieved that the loosened contaminants are not uncontrollably displaced to random locations within the device, causing disturbances. It is advantageous that the device for receiving the contaminants be connected with a suction device.
In further developments of the invention there are provided means for reversing the rotational direction of at least one of the rollers, which preferably is controlled from the maintenance unit. Thereby an improved cleaning, especially of the wedge-shaped gap, is achieved.
Further objects, features, and advantages of the present invention will become more apparent from the following description when taken with the accompanying drawings which show, for purposes of illustration only, an embodiment in accordance with the present invention.